[Big Bad Bob]

On 01/19/16 22:51, Patrick Turner so wittily quipped:
This means that for a given B+, RLa and Ea and Ia, BH7 can swing a wider voltage before Ea swing is limited by Ra curve for Eg1 = 0V. The lower Ra means F response extends to higher F. Because it swings wide, its an ideal driver for output stages needing high Ea swing, such as in McIntosh amps.

that's an interesting description of possible usage in audio amps. I
was looking more at its intended function, but that being said,
deflection amplifiers would need to have large signal linearity or you
get a distorted picture.

Being designed for (in essence) a current source for horizontal or
vertical deflection oscillator [or apparently a vertical deflection
output stage?] it would have to use a larger linear region to make the
sweep flat. That being said, "wider voltage swing" makes sense.

I wouldn't be surprised to see these in old B&W sets from the 1950's.